Electronic structure and optical properties ofLiB3O5

The band structure and the interband optical conductivity of a ${\mathrm{LiB}}_3$ ${\mathrm{O}}_5$ crystal with excellent nonlinear optical properties are studied by means of a first-principles method. The electronic structure is characterized by highly localized bands with a direct gap of 7.37 eV at Γ and a very low static dielectric constant of 2.7. The optical absorption curve shows several prominent structures but with very small directional anisotropy. The calculated frequency-dependent refractive index is in good agreement with experimental data.